Common distance measuring methods include direct measuring and indirect measuring. In a direct measuring method, a measurer directly measures a distance between objects by utilizing a ruler. Such measuring method frequently incurs a measuring error due to different operations of measurers. In an indirect measuring method, the measuring process may be performed by an apparatus cooperating with a benchmark to calculate a distance between objects according to angles corresponding to the objects. Although the indirect measuring method renders a higher accuracy than the direct measuring method, the indirect measuring method nevertheless encounters operation inconveniences in actual applications due to environmental restrictions and a requirement of two measurers.
Other distance detection methods are developed in the recent years, e.g., distance detection through sound waves, radio waves or lasers. Among the above distance detection methods, the laser distance measuring method, featuring high accuracy, capability of clearly demarcating a detection point and ease of use, prevails in application of transportation, architecture and topographic surveys. Taking a laser rangefinder for example, a fundamental principle is as described below. A laser transmitter first emits a laser beam towards an object, a laser receiver receives a signal reflected from the object, and a time difference between the emitted laser beam and the received reflected signal is calculated and analyzed to obtain a distance between the laser rangefinder and the object. However, rather than measuring distances between the laser rangefinder and several detection points, a common laser rangefinder is capable of only measuring a distance between the laser rangefinder and one single object per measuring process, thus limiting an application scope of the laser measuring method.